


Courtship by Capture

by EmberSparks



Category: Supernatural
Genre: ABO, Alpha!Dean, Animalistic, Destiel - Freeform, Exploring, First Time, Hybrid AU, Hybrids, Intersex, Knotting, M/M, Mating, Mermen, Omegaverse, Ritualistic, Smut, beta!cas, courting, courtship by capture, different version of beta, fish hybrid, human hybrid, mer!cas, merman, octo - Freeform, octo!Dean, octomen
Language: English
Status: Completed
Published: 2016-07-19
Updated: 2016-07-19
Packaged: 2018-07-25 08:49:56
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,667
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7526263
Author URL: https://archiveofourown.org/users/EmberSparks/pseuds/EmberSparks
Summary: <blockquote class="userstuff">
              <p>Castiel is a perfectly innocent merman beta...until a very curious, very cute Octo catches him by surprise.</p>
            </blockquote>





	Courtship by Capture

**Author's Note:**

> Warning: some might consider this dub-con, animalistic mating.

 

The last thing Castiel remembered was arguing with Michael. It was just nagging between brothers; the older alpha asserting his dominance and the younger beta ignoring him. No one expected the attack.

The little envoy of mermen returning to their home was suddenly swarmed by a territorial octo hunting party. Castiel was never trained to defend himself and somehow the black-finned Merman found himself separated from the pack. Suddenly something thick and green was covering his eyes and mouth, and he felt the water rushing past the gills on his neck, meaning he was being dragged away. The beta panicked and fought. But it was no use. The Octo that had him was bigger and stronger and smirking from ear to ear as he shoved his prize into a nearby cave.

“Let go of me!”

  
The merman hissed, his scales standing on end as he tried to look fierce. His kind were not strong though. They were fast. But speed would do him no good in the narrow cave, especially not with a grinning octo spreading his tentacles, blocking the only way out.

“Not gonna hurt ya lil fishie….just wanna ask some stuff,”

He gave another little smirk, his eyes going over the merman from tip to tail, curious almost, like a malevolent child. Octos weren’t evil per se. They were crude, and they were violent, and they were animalistic at best. Never got a long with the prudish, civilized merpeople.

Just then the octo reached out one of his many emerald green libs, curling it around Castiel’s tail, and pulling it upward. The beta’s head spun. Even underwater, being inverted was disorienting. And having those squishy suction cups moving along his scales was weird.

“You captured me, simply to ask questions?”

Castiel shook his tail, righting himself even as he backed further into the cave. They must be deep into octo territory. He’d never been here, not that he could see much of here past the creature anyway, and not particularly well in the dark.

“Told you, curious.”

The green eyes were the same color as his lower half, both equally bright in to see in the dark. Castiel was still being herded back, and maybe it was his imagination but he thought the cave was getting just a little lighter. Maybe his eyes were just adjusting. The tentacle still had the merman by the tail, this time leaving him upright, but bringing the fin up so it could play with his fin between his fingers. Castiel would laugh at that if his heart weren’t pounding.

“You did not have to take me away just because you were curious, and stop that!” he flicked his tail fin, slapping at the tickling fingers. “I am a merman not a fish! Stop touching me with those.”

The beta tried to look furious at the continued prodding, but it came off more as a pout. He didn’t feel so much in danger as he did….curious? Castiel had never seen an octo up close, his siblings had always babied him too much to ever let him get near one….and they weren’t, actually, as ugly as he’d imagined. In fact, this one was rather beautiful. At least he would be if he were a merman of course.

The octo was busy laughing at the little face Castiel had made. He spread all of his tentacles wide, wiggling them at his captive with a big goofy grin on his face.

“Tickle tickle” he chuckled, advancing on the merman still closer this time. “And hey, we’re awesome. Some octos even change color- haven’t figure out that trick yet.”

The blond creature paused a moment, looking puzzled as if he were trying to figure it out for a moment, before he launched at Castiel, sending him flying backward. He expected to be knocked out against a cave wall - but instead the fishman found himself a nice soft landing in… was he in a sand bed?

It was warm, and it was soft, even rather nice with the light coming down from the surface. The grains were fine and white. It might even be relaxing, if present company weren’t back on his tail, prodding his tentacles up his scales none too slowly.

“I’m Dean, and I like sand baths” the octo said proudly, puffing out his chest as he moved around, back over the merman, sitting on his fin to keep him still. “Octos loooove sand baths”

His tentacles were even brighter in the sunlight. They began shoveling up little piles of sand, then massaging them up along the merman’s inky black scales. Castiel was actually enjoying the warmth of the sand. Then he started feeling more limbs wrapping around his wrists.

“Only children take sand baths, they’re babyish,"

The merman wrinkled his nose… even though the gentle massaging was starting to feel quite nice between his scales, cleaning and polishing them gently. Castiel still squirmed. But this time, a little whine left his lips when the prodding moved up along his lap.

“I haven’t had a sand bath since I was a child. I haven’t been given one since I was- Are all octos this touchy!?”

“Yep, what'd ya think all these suckers are for?”

Dean was still chuckling, popping the little suction cups on his tentacles under the merman’s nose, before they were moving along the skin of his torso, his cheeks, even through his dark hair. That… felt rather nice actually, even if it was sort of like being petted. The beta was embarrassed to even think of that.

“My name is Castiel, Prince Castiel. When do you plan on letting me go Dean, I think I’m quite done with you," the merman huffed, despite the pink in his cheeks.

The octo stuck out his tongue.

“You are not, Princy-Fins” Dean was leaning more over him now. Castiel noticed the suckers were leaving little pink marks when they popped free of his skin. “And I’ll let you go when we’re done playing!”

“You call this playing?” Castiel snorted.

It was clear why Michael referred to the Octos as the many legged savages; they didn’t seem all that bright. But Dean was strong as could be. The tentacles didn’t seem tight around Castiel’s hands at all, but if he ever pulled away he was stuck like a barnacle to a rock.

And apparently the mermen and octos had very different definitions of what playing meant as well, which became crystal clear when Dean’s webbed fingered hand pressed bold as brass to the scales of Castiel’s lap, and he asked.

“So Cas, where you hiding your dick then?”

“Excuse me!” The merman’s torso was now entirely red. “I think that’s…highly inappropriate of you to ask!” He huffed, now inches from Dean’s curious face. When did the octo get him on his back… with his head dangerously near Castiel’s lap?

“Whaaat? I told you I was curious. Can’t just go up and ask any old fish boy," the Octo was grinning from ear to ear.

Castiel heard rumors, of the barbaric nature of octos. That they were blunt and rude sure, but that their courting rituals often ended up with rivals bloodied. That the omegas were to be chased, and caught, like… like in a hunting party. The mermen were complete prudes by comparison. They’d never ask such a thing, never have… have hands in those places. Castiel was too flustered to speak.

“Heard y’all have both parts sometimes. That’s sooo weird.”

Dean’s tentacles were swishing around them both in excitement, stirring up little billows of sand. But he looked when Castiel made a sound. A sound he tried to bite back and hide.

The octo gave an even more excited grin, continuing his petting, practically grinding his palm down along the merman’s sensitive sheath. Castiel was humiliated by how good that felt.

“I..yes, yes some of us… do. Betas, have both. I’m a beta… and we keep them behind our sheaths, since it would be rude to bring out one’s privates in public which is what you’re about to do right now-!”

“Aww, yes! I knew I picked a good one” the octo pumped his fist. But all to soon his full attention to turned back to Castiel’s lap. To the merman’s utter shamed the petting had gotten him aroused, so that his scales started to slide apart, about to bare himself for the world to see.

“C’mon Cas…this ain’t a public place” the blonde purred, still low over the merman’s lap, smirking up at the bright blue eyes. “I’ll show you mine if you show me yours”

Castiel felt a rush of curiosity and arousal when Dean said that, when he looked up at him like that.

“We’re… only supposed to show them… to people we wish to mate with” the merman protested feebly, but he nodded his agreement to the deal.

It was already too late, anyway. His cock was far to interested, peeking up through his scales… and honestly, he really wanted to see Dean’s. Just showing couldn’t hurt.

“My…hole, is right under. So I can use either… as needed” he was burning up now, too embarrassed to finish. Already leaning up to sheath his privates once again.

Really, the merman should have known better than to trust a curious octo.

“Ooooo look at that, it’s such a boring color!” Dean trilled.

“Dean!”

And just like that, Dean’s long fingers were around the fleshy colored appendage, playing with it, stroking it, rubbing his webbed thumb along the head. Giving Castiel the first real pleasure he’d had in his life.

“You can’t… just reach out like that”

The merman’s protest was feeble at best. He threw his head back, letting out a low, instinctive sound. Around him the world seemed to ripple. Not unusual for water, but Cas was surrounded with Dean’s green squishy body, which somehow was turning even brighter.

Castiel was utterly conflicted. Nothing felt as good as this strange creature playing with him…but he’d been told his whole life sex was for laying eggs only. Not supposed to feel like…like playing.

“I guess it’s not supposed to be exciting, since y’all don’t use it that much anyway.” The octo gave little shrug. “Poor thing never gets played with!”

Castiel gasped when Dean was suddenly face first in his lap. He felt the other’s lips around his cock, and the merman became a shuddering mess. The tentacles released his hands, and the immediately went into the blonde hair.

“D-Deann… this is how you play?”

The octo’s extra limbs were flaring out now, ringing different shades of green and displaying eagerly. Castiel was biting on his lip. He only wanted more of whatever that was Dean was doing with his mouth, but the octo pulled away. He wasn’t wrong; Cas was having a lot of fun, a lot of fun.

“So can I see your hole now? Or do you wanna see my dick?”

“My… hole, is right behind my cock” The merman lifted himself, showing Dean that his entrance was slick and swollen, ready to be mated. “I want to see what your cock looks like” Castiel nodded at once.

The octo had already leaned forward, like he was about to bury his face in the beta’s lap- but he was an alpha octo after all. He’d never miss a chance to display himself. Even if it seemed he still wanted to touch Castiel.

Dean reared back, his tentacle’s sliding around the merman’s waist, tugging him closer, and nudging their tips back into his sheath. Under all the extra limbs the octo had a pale underbelly, and a wring of still appendages. From that, his long, thick cock emerged, ringing in the brightest colors Castiel had ever seen.

“It’s so… pretty,”  
T he merprince never thought he would ever say anything like that.

“Should be pretty, so you wanna play with it more” the octo reasoned simply.  
He let Castiel get as close as he wanted to be, but the merman's eyes were suddenly on the alpha's lips.

Then, Cas was kissing Dean. He felt the octo stiffen, utterly shocked. He pulled back quickly…and Dean looked surprised, like he was more expecting being bitten than being kissed. Come to think of it, he probably was. Then he grinned. And tentacles were invading Castiel’s entrance.

The merman let out a gasp, wrapping his arms around the octo’s shoulders, pulling him tight and kissing him feverishly, shuddering with pleasure.

“Dean…you feel so nice”

The merman wriggled his hips, craving more of the stretch and pressure as the octo began working him open, playing with his slick folds.

“You’re nicer”

Dean countered, leaning in himself this time, and giving his best sloppy kiss. “Octos are never nice” he murmured, nipping Castiel a little in his attempts to imitate him. “Nice…can be good”

“You are good Dean, so good” Castiel whined a little, clutching to Dean as he sped his movements, fucking the merman thoroughly. He was out of his mind, lust filled and needy. “Please, I want you”

“You can have me,”

The octo was purring, his tentacles vibrating and starting to wave a deep blue ring with his brightest emerald. He didn’t hesitate to move Castiel into his lap, moving the merman’s hips with his hands. He pulled the tentacles away as he pressed the beta down onto his cock slowly.

“Doesn’t hurt, if you do it right,”

Castiel figured that was supposed to be an octo’s version of comforting. He managed to nod, before he was pressing his face to Dean’s neck, holding tight to him, letting out guttural sounds as he sank down onto the octo’s cock.

“Dean” the merman purred, kissing him and wriggling his hips as he got used to being filled. He’d never mated before, but he knew this wasn't how a meralpha felt. This was so much better. Dean was kissing him back and being as gentle as an octo could manage. He could feel tentacles sliding up and down along his skin, leaving little marks with their suckers, comforting him and distracting him, until he murmured.

“More… please.”

Merpeople, were never supposed to be rough. They did not fight, and they certainly did not play rough. They never fucked rough because that was your treasured mate. The one you’d spend your life with.

Octos were not mermen.

And Castiel liked that, he liked it a lot.

Dean was quick and sloppy and entirely in control. His tentacles wrapped back around the merman’s waist, bringing him up and down on the octo’s cock. He sped his movements as Castiel quickly came undone. When the beta was too lost to speak, he found himself pinned down to the ground.

Dean’s hips bucked hard and fast, fucking him properly, his knot catching Castiel’s hole. The trapped fin wriggled. Cas tried pressing up to the movements, but he was utterly overwhelmed. They were both devolving int whines and moans. Dean fucked into him harshly, and it was perfect in every way-

Castiel had not expected Dean’s impulse control to be very high. He could feel it, when he blinked his way out of oblivion, the alpha’s knot locking them together. The merman was warm inside….and a glob of white floated in the water before his eyes.

The merman swatted his come away, but he was far to content to be embarrassed. He gave a tug to the blonde hair. Dean hummed, leaning up lazily, dropping a few kisses along Castiel’s skin.

“Nice is good” he murmured against the merman’s lips.

“Nice is very good” Castiel agreed with a chuckle.

Dean wrapped his merman up in all of his limbs, tangling them together, rolling onto his side so they were both comfortable in their sand bed. Castiel was calming down. His gills stopped fluttering along his neck….and he hid his head in the octo’s chest.

“This…is not going to be easy to explain to Michael”

 

 

 

 

 

 

**Author's Note:**

> Based off an RP with Kyla
> 
> Unbeta'd, let me know if there are any mistakes :)  
> thanks for reading!


End file.
